In conventional turret-type punch press machines, a workpiece feeding apparatus for feeding a plate workpiece on a table to a punching position includes a workpiece holder that is moved while gripping a workpiece.
A condition such as the size of a workpiece or a punching position on the workpiece may require the workpiece feeding apparatus to perform a repositioning operation for repositioning the workpiece to change the gripping position of the workpiece holder. During such a repositioning operation, since the workpiece may become offset if it is slightly released from the workpiece holder, a pair of friction pads that can be elevated and lowered by an elevating cylinder are provided and used to press the workpiece against the table to prevent such offset.
When the frictional force of the friction pads is used to fix the workpiece against the table as described above, the workpiece is not properly fixed and can get offset while being re-gripped by the workpiece holder.
The present invention is designed to solve the above-described problem and to provide a press machine capable of reliably repositioning the workpiece without causing it to be offset.